Microwave and millimeter wave circuits may use a combination of rectangular and/or circular waveguides and planar transmission lines such as striplines, microstrips, and co-planar waveguides. Waveguides are commonly used, for example, in antenna feed networks. Microwave circuit modules typically use microstrip transmission lines to interconnect microwave integrated circuits and semiconductor devices mounted on planar substrates. Transition devices are used to couple signals between microstrip transmission lines and waveguides.
This “Discussion of the Background” section is provided for background information only. The statements in this “Discussion of the Background” are not an admission that the subject matter disclosed in this “Discussion of the Background” section constitutes prior art to the present disclosure, and no part of this “Discussion of the Background” section may be used as an admission that any part of this application, including this “Discussion of the Background” section, constitutes prior art to the present disclosure.